1. Field of the Invention
The present invention relates to a power supply apparatus for magnetron driving in a micro-wave oven, and more particularly to a power supply apparatus for driving a magnetron in the micro-wave oven wherein damages wrought on magnetrons by the overcurrent can be prevented by applying stable currents to a power supply apparatus for driving a magnetron which employs S.M.P.S. (Switching Mode Power supply) system.
2. Description of the Prior Art
Generally, high voltages are needed to drive a magnetron of a micro-wave oven and high-voltage transformers or inverters are used for generating high voltages.
A power supply apparatus for magnetron driving employing an inverter is described in Japanese laid open patent application NO. 53-27143, entitled "the power supply apparatus for driving magnetron".
According to Japanese laid open patent application NO. 53-27143, the power supply apparatus for driving a magnetron is composed of a frequency oscillation circuit which can change duty cycles of output signals, a high frequency oscillation circuit which controls signal transfer or signal oscillation according to output signals from a frequency oscillation circuit and a switching circuit being switched according to the signals from high frequency oscillation ciruits. Miniaturization lightening and reduced cost of the output transformer can be realized.
However, this kind of inverter-type power supply apparatus for magnetron driving has disadvantages including unstable output voltages against the load and voltage changes which causes damage to the magnetron. Further, when a high voltage transformer is used, the power supply apparatus tends to become bulky and heavy as it generates high voltages.
Accordingly, it is an object of the present invention to provide a power supply apparatus for driving a magnetron which can supply stable electric power to prevent damages on the magnetron by overcurrents, while at the same time providing a miniaturized power supply apparatus as well.